I. Field of the Invention
The present invention relates to a thin film magnetic head of a magnetoresistive type to be used for recording and playing back a digital signal.
II. Description of the Prior Art
Conventionally, a magnetoresistive head (to be referred to as an MR head) has been proposed which comprises a magnetoresistive element (to be referred to as an MR element hereinafter) of a thin strip-shaped ferromagnetic plate.
The MR head is generally mounted together with a thin magnetic induction recording head in the same tape deck, or is deposited together with the thin magnetic induction recording head on the same substrate. In either case, these heads are arranged to be adjacent to each other. However, "feed through" occurs wherein a recording current is mixed in a reproduction output, so that a data signal may not be reproduced by a "real time" monitor which monitors recording sounds. When a shield type MR head having magnetic gaps at two sides of the MR element is used to decrease the feed through signal and to perform short-wave signal reproduction, a constant external magnetic field must be intense enough to bias the MR element since the MR head is shielded. As a result, the signals recorded on the recording medium are demagnetized. Furthermore, the shielding effect is not sufficient to prevent feed through. Therefore, the recording sounds cannot be simultaneously monitored in practice.
In an MR head adopting a shunt bias method which is one of several current bias methods, strict requirements are demanded such as uniformity of the element, uniformity of the recording signals, and azimuth alignment which gives rise to problems in interchangeability among equipment, as compared with requirements of a head having any other structure. Furthermore, thermal noise inherent to the MR element often occurs, thus resulting in an impractical MR head.